diff --git a/modules/NavBarHeight/linux/tt-navbar-24.css b/modules/NavBarHeight/linux/tt-navbar-24.css
index e880548..0fb2452 100644
--- a/modules/NavBarHeight/linux/tt-navbar-24.css
+++ b/modules/NavBarHeight/linux/tt-navbar-24.css
@@ -25,9 +25,6 @@ window:not([chromehidden~="toolbar"]) #urlbar-wrapper {
 /* 271 */
 
 /* Use smaller back button icon */
-#back-button {
-	-moz-image-region: rect(0, 54px, 18px, 36px);
-}
 
 /* 369 */
 
@@ -90,5 +87,10 @@ window:not([chromehidden~="toolbar"]) #urlbar-wrapper {
 /* fix for #220 (Firefox 55 - back button missing) */
 
 #back-button {
-	list-style-image: url(chrome://tabtree/skin/Toolbar.png);
+	list-style-image: url(chrome://browser/skin/back.svg);
+}
+
+#back-button > .toolbarbutton-icon {
+	padding-top: 3px !important;
+	padding-bottom: 3px !important;
 }
diff --git a/modules/NavBarHeight/linux/tt-navbar-26.css b/modules/NavBarHeight/linux/tt-navbar-26.css
index d2a7460..115a254 100644
--- a/modules/NavBarHeight/linux/tt-navbar-26.css
+++ b/modules/NavBarHeight/linux/tt-navbar-26.css
@@ -25,9 +25,6 @@ window:not([chromehidden~="toolbar"]) #urlbar-wrapper {
 /* 271 */
 
 /* Use smaller back button icon */
-#back-button {
-	-moz-image-region: rect(0, 54px, 18px, 36px);
-}
 
 /* 369 */
 
@@ -79,5 +76,10 @@ window:not([chromehidden~="toolbar"]) #urlbar-wrapper {
 /* fix for #220 (Firefox 55 - back button missing) */
 
 #back-button {
-	list-style-image: url(chrome://tabtree/skin/Toolbar.png);
+	list-style-image: url(chrome://browser/skin/back.svg);
+}
+
+#back-button > .toolbarbutton-icon {
+	padding-top: 3px !important;
+	padding-bottom: 3px !important;
 }
diff --git a/modules/NavBarHeight/linux/tt-navbar-28.css b/modules/NavBarHeight/linux/tt-navbar-28.css
index a52ecea..eb56a6e 100644
--- a/modules/NavBarHeight/linux/tt-navbar-28.css
+++ b/modules/NavBarHeight/linux/tt-navbar-28.css
@@ -25,9 +25,6 @@ window:not([chromehidden~="toolbar"]) #urlbar-wrapper {
 /* 271 */
 
 /* Use smaller back button icon */
-#back-button {
-	-moz-image-region: rect(0, 54px, 18px, 36px);
-}
 
 /* 369 */
 
@@ -79,5 +76,10 @@ window:not([chromehidden~="toolbar"]) #urlbar-wrapper {
 /* fix for #220 (Firefox 55 - back button missing) */
 
 #back-button {
-	list-style-image: url(chrome://tabtree/skin/Toolbar.png);
+	list-style-image: url(chrome://browser/skin/back.svg);
+}
+
+#back-button > .toolbarbutton-icon {
+	padding-top: 3px !important;
+	padding-bottom: 3px !important;
 }
diff --git a/modules/NavBarHeight/linux/tt-navbar-30.css b/modules/NavBarHeight/linux/tt-navbar-30.css
index ce05c9f..2b2f903 100644
--- a/modules/NavBarHeight/linux/tt-navbar-30.css
+++ b/modules/NavBarHeight/linux/tt-navbar-30.css
@@ -25,9 +25,6 @@ window:not([chromehidden~="toolbar"]) #urlbar-wrapper {
 /* 271 */
 
 /* Use smaller back button icon */
-#back-button {
-	-moz-image-region: rect(0, 54px, 18px, 36px);
-}
 
 /* 369 */
 
@@ -58,5 +55,10 @@ window:not([chromehidden~="toolbar"]) #urlbar-wrapper {
 /* fix for #220 (Firefox 55 - back button missing) */
 
 #back-button {
-	list-style-image: url(chrome://tabtree/skin/Toolbar.png);
+	list-style-image: url(chrome://browser/skin/back.svg);
+}
+
+#back-button > .toolbarbutton-icon {
+	padding-top: 3px !important;
+	padding-bottom: 3px !important;
 }
diff --git a/modules/NavBarHeight/windows/tt-navbar-24.css b/modules/NavBarHeight/windows/tt-navbar-24.css
index 84be788..97b25f5 100644
--- a/modules/NavBarHeight/windows/tt-navbar-24.css
+++ b/modules/NavBarHeight/windows/tt-navbar-24.css
@@ -32,9 +32,6 @@ window:not([chromehidden~="toolbar"]) #urlbar-wrapper {
 /* 271 */
 
 /* Use smaller back button icon */
-#back-button {
-	-moz-image-region: rect(0, 54px, 18px, 36px);
-}
 
 /* 378 */
 
@@ -100,5 +97,10 @@ window:not([chromehidden~="toolbar"]) #urlbar-wrapper {
 /* fix for #220 (Firefox 55 - back button missing) */
 
 #back-button {
-	list-style-image: url(chrome://tabtree/skin/Toolbar.png);
+	list-style-image: url(chrome://browser/skin/back.svg);
+}
+
+#back-button > .toolbarbutton-icon {
+	padding-top: 3px !important;
+	padding-bottom: 3px !important;
 }
diff --git a/modules/NavBarHeight/windows/tt-navbar-26.css b/modules/NavBarHeight/windows/tt-navbar-26.css
index 29abe86..79f6306 100644
--- a/modules/NavBarHeight/windows/tt-navbar-26.css
+++ b/modules/NavBarHeight/windows/tt-navbar-26.css
@@ -32,9 +32,6 @@ window:not([chromehidden~="toolbar"]) #urlbar-wrapper {
 /* 271 */
 
 /* Use smaller back button icon */
-#back-button {
-	-moz-image-region: rect(0, 54px, 18px, 36px);
-}
 
 /* 378 */
 
@@ -80,5 +77,10 @@ window:not([chromehidden~="toolbar"]) #urlbar-wrapper {
 /* fix for #220 (Firefox 55 - back button missing) */
 
 #back-button {
-	list-style-image: url(chrome://tabtree/skin/Toolbar.png);
+	list-style-image: url(chrome://browser/skin/back.svg);
+}
+
+#back-button > .toolbarbutton-icon {
+	padding-top: 3px !important;
+	padding-bottom: 3px !important;
 }
diff --git a/modules/NavBarHeight/windows/tt-navbar-28.css b/modules/NavBarHeight/windows/tt-navbar-28.css
index a49db15..724d4f9 100644
--- a/modules/NavBarHeight/windows/tt-navbar-28.css
+++ b/modules/NavBarHeight/windows/tt-navbar-28.css
@@ -32,9 +32,6 @@ window:not([chromehidden~="toolbar"]) #urlbar-wrapper {
 /* 271 */
 
 /* Use smaller back button icon */
-#back-button {
-	-moz-image-region: rect(0, 54px, 18px, 36px);
-}
 
 /* 378 */
 
@@ -73,5 +70,10 @@ window:not([chromehidden~="toolbar"]) #urlbar-wrapper {
 /* fix for #220 (Firefox 55 - back button missing) */
 
 #back-button {
-	list-style-image: url(chrome://tabtree/skin/Toolbar.png);
+	list-style-image: url(chrome://browser/skin/back.svg);
+}
+
+#back-button > .toolbarbutton-icon {
+	padding-top: 3px !important;
+	padding-bottom: 3px !important;
 }
diff --git a/modules/NavBarHeight/windows/tt-navbar-30.css b/modules/NavBarHeight/windows/tt-navbar-30.css
index d499676..1116fec 100644
--- a/modules/NavBarHeight/windows/tt-navbar-30.css
+++ b/modules/NavBarHeight/windows/tt-navbar-30.css
@@ -32,9 +32,6 @@ window:not([chromehidden~="toolbar"]) #urlbar-wrapper {
 /* 271 */
 
 /* Use smaller back button icon */
-#back-button {
-	-moz-image-region: rect(0, 54px, 18px, 36px);
-}
 
 /* 378 */
 
@@ -73,5 +70,10 @@ window:not([chromehidden~="toolbar"]) #urlbar-wrapper {
 /* fix for #220 (Firefox 55 - back button missing) */
 
 #back-button {
-	list-style-image: url(chrome://tabtree/skin/Toolbar.png);
+	list-style-image: url(chrome://browser/skin/back.svg);
+}
+
+#back-button > .toolbarbutton-icon {
+	padding-top: 3px !important;
+	padding-bottom: 3px !important;
 }
diff --git a/skin/Toolbar.png b/skin/Toolbar.png
deleted file mode 100644
index b191ce2..0000000
Binary files a/skin/Toolbar.png and /dev/null differ